/*
 * Copyright 2001-2005 (C) MetaStuff, Ltd. All Rights Reserved.
 *
 * This software is open source.
 * See the bottom of this file for the licence.
 */

package com.googlecode.bluetools.dom4j.io;

import java.util.ArrayList;
import java.util.HashMap;

import com.googlecode.bluetools.dom4j.Element;
import com.googlecode.bluetools.dom4j.ElementHandler;
import com.googlecode.bluetools.dom4j.ElementPath;

/**
 * <p>
 * <code>DispatchHandler</code> implements the <code>ElementHandler</code> interface and provides a means to register
 * multiple <code>ElementHandler</code> instances to be used by an event based processor. This is a special
 * <code>ElementHandler</code> in that it's <b>onStart </b> and <b>onEnd </b> implementation methods are called for
 * every element encountered during the parse. It then delegates to other <code>ElementHandler</code> instances
 * registered with it to process the elements encountered.
 * </p>
 * 
 * @author <a href="mailto:dwhite@equipecom.com">Dave White </a>
 * @version $Revision: 1.1 $
 */
class DispatchHandler implements ElementHandler {
	/** Whether the parser is at the root element or not */
	private boolean atRoot;

	/** The current path in the XML tree (i.e. /a/b/c) */
	private String path;

	/** maintains a stack of previously encountered paths */
	private ArrayList pathStack;

	/** maintains a stack of previously encountered handlers */
	private ArrayList handlerStack;

	/**
	 * <code>HashMap</code> maintains the mapping between element paths and handlers
	 */
	private HashMap handlers;

	/**
	 * <code>ElementHandler</code> to use by default for element paths with no handlers registered
	 */
	private ElementHandler defaultHandler;

	public DispatchHandler() {
		atRoot = true;
		path = "/";
		pathStack = new ArrayList();
		handlerStack = new ArrayList();
		handlers = new HashMap();
	}

	/**
	 * Adds the <code>ElementHandler</code> to be called when the specified path is encounted.
	 * 
	 * @param handlerPath is the path to be handled
	 * @param handler is the <code>ElementHandler</code> to be called by the event based processor.
	 */
	public void addHandler(String handlerPath, ElementHandler handler) {
		handlers.put(handlerPath, handler);
	}

	/**
	 * Removes the <code>ElementHandler</code> from the event based processor, for the specified path.
	 * 
	 * @param handlerPath is the path to remove the <code>ElementHandler</code> for.
	 * 
	 * @return DOCUMENT ME!
	 */
	public ElementHandler removeHandler(String handlerPath) {
		return (ElementHandler) handlers.remove(handlerPath);
	}

	/**
	 * DOCUMENT ME!
	 * 
	 * @param handlerPath DOCUMENT ME!
	 * 
	 * @return true when an <code>ElementHandler</code> is registered for the specified path.
	 */
	public boolean containsHandler(String handlerPath) {
		return handlers.containsKey(handlerPath);
	}

	/**
	 * Get the registered {@link ElementHandler}for the specified path.
	 * 
	 * @param handlerPath XML path to get the handler for
	 * 
	 * @return the registered handler
	 */
	public ElementHandler getHandler(String handlerPath) {
		return (ElementHandler) handlers.get(handlerPath);
	}

	/**
	 * Returns the number of {@link ElementHandler}objects that are waiting for their elements closing tag.
	 * 
	 * @return number of active handlers
	 */
	public int getActiveHandlerCount() {
		return handlerStack.size();
	}

	/**
	 * When multiple <code>ElementHandler</code> instances have been registered, this will set a default
	 * <code>ElementHandler</code> to be called for any path which does <b>NOT </b> have a handler registered.
	 * 
	 * @param handler is the <code>ElementHandler</code> to be called by the event based processor.
	 */
	public void setDefaultHandler(ElementHandler handler) {
		defaultHandler = handler;
	}

	/**
	 * Used to remove all the Element Handlers and return things back to the way they were when object was created.
	 */
	public void resetHandlers() {
		atRoot = true;
		path = "/";
		pathStack.clear();
		handlerStack.clear();
		handlers.clear();
		defaultHandler = null;
	}

	/**
	 * DOCUMENT ME!
	 * 
	 * @return the current path for the parse
	 */
	public String getPath() {
		return path;
	}

	// The following methods implement the ElementHandler interface
	public void onStart(ElementPath elementPath) {
		Element element = elementPath.getCurrent();

		// Save the location of the last (i.e. parent) path
		pathStack.add(path);

		// Calculate the new path
		if (atRoot) {
			path = path + element.getName();
			atRoot = false;
		}
		else {
			path = path + "/" + element.getName();
		}

		if ((handlers != null) && (handlers.containsKey(path))) {
			// The current node has a handler associated with it.
			// Find the handler and save it on the handler stack.
			ElementHandler handler = (ElementHandler) handlers.get(path);
			handlerStack.add(handler);

			// Call the handlers onStart method.
			handler.onStart(elementPath);
		}
		else {
			// No handler is associated with this node, so use the
			// defaultHandler it it exists.
			if (handlerStack.isEmpty() && (defaultHandler != null)) {
				defaultHandler.onStart(elementPath);
			}
		}
	}

	public void onEnd(ElementPath elementPath) {
		if ((handlers != null) && (handlers.containsKey(path))) {
			// This node has a handler associated with it.
			// Find the handler and pop it from the handler stack.
			ElementHandler handler = (ElementHandler) handlers.get(path);
			handlerStack.remove(handlerStack.size() - 1);

			// Call the handlers onEnd method
			handler.onEnd(elementPath);
		}
		else {
			// No handler is associated with this node, so use the
			// defaultHandler it it exists.
			if (handlerStack.isEmpty() && (defaultHandler != null)) {
				defaultHandler.onEnd(elementPath);
			}
		}

		// Set path back to its parent
		path = (String) pathStack.remove(pathStack.size() - 1);

		if (pathStack.size() == 0) {
			atRoot = true;
		}
	}
}

/*
 * Redistribution and use of this software and associated documentation ("Software"), with or without modification, are
 * permitted provided that the following conditions are met:
 * 
 * 1. Redistributions of source code must retain copyright statements and notices. Redistributions must also contain a
 * copy of this document.
 * 
 * 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the
 * following disclaimer in the documentation and/or other materials provided with the distribution.
 * 
 * 3. The name "DOM4J" must not be used to endorse or promote products derived from this Software without prior written
 * permission of MetaStuff, Ltd. For written permission, please contact dom4j-info@metastuff.com.
 * 
 * 4. Products derived from this Software may not be called "DOM4J" nor may "DOM4J" appear in their names without prior
 * written permission of MetaStuff, Ltd. DOM4J is a registered trademark of MetaStuff, Ltd.
 * 
 * 5. Due credit should be given to the DOM4J Project - http://www.dom4j.org
 * 
 * THIS SOFTWARE IS PROVIDED BY METASTUFF, LTD. AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL METASTUFF, LTD. OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * 
 * Copyright 2001-2005 (C) MetaStuff, Ltd. All Rights Reserved.
 */
